Mesa 5i25 7i77 Limit Switch True when not limit

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01 Feb 2017 00:33 #87104 by B.Reilly01
B.Reilly01 created the topic: Mesa 5i25 7i77 Limit Switch True when not limit
My machine has NPN limit switches that show ground when limit is reached, and float when not on the limit. I understand that MESA prefers (requires?) limit switches to show +FV when at the limit. Is it possible to configure an input as true when NOT at limit and use a pullup resistor to make the output of my limitswitches +FV when off limit and 0V (false) when at the limit? I'd prefer not incorporating ANOTHER relay board just to flip the logic of my limitswitches.
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01 Feb 2017 01:09 #87106 by PCW
PCW replied the topic: Mesa 5i25 7i77 Limit Switch True when not limit
Yes NPN limits need a pullup resistor (say 2K 1W) to interface with the 7I77s digitalinputs

To invert the logic you just connect the limit signals to the hm2_5i25.0.7i77.0.0.input-XX-not
pins instead of the hm2_5i25.0.7i77.0.0.input-XX pins in the hal file
The following user(s) said Thank You: B.Reilly01
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01 Feb 2017 01:11 #87107 by tommylight
tommylight replied the topic: Mesa 5i25 7i77 Limit Switch True when not limit
Every input on mesa boards has an in and in-not pin, so you can use a pull up resistor and use in-not for that pin.
The following user(s) said Thank You: B.Reilly01
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01 Feb 2017 01:12 #87108 by B.Reilly01
B.Reilly01 replied the topic: Mesa 5i25 7i77 Limit Switch True when not limit
Great, so I build my PNCConf files, then I edit the HAL to switch the limits to the NOT pin instead of the regular pin.
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01 Feb 2017 01:25 #87109 by tommylight
tommylight replied the topic: Mesa 5i25 7i77 Limit Switch True when not limit
Yes, and i think you can also do that in pncconfig.
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01 Feb 2017 01:48 #87111 by B.Reilly01
B.Reilly01 replied the topic: Mesa 5i25 7i77 Limit Switch True when not limit
Got it, the INV box
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